Also I wonder about the real horizontal FOV for each mode. "Ultra wide" means nothing to me and nor does "normal" or "Narrow"

Can anyone help me out with how all this works. The way I see it is that the camera has a fixed lens and a 4K sensor. Therefore At 4k you can only get the "Ultra wide" FOV while at 1080p you can choose to have narrower FOV's because the processor simply picks the 1080p sized area on the 4K sensor depending on the FOV selected. Full "Ultra wide" at 1080p would mean the processor is taking every second pixel on every second row to form the 1080p image etc.

That would explain the weird 2.7k video option. I want these cameras to run at 2.7k with a HFOV of 90 degrees. I suppose that means a replacement lens.

I wonder if the older aftermarket lenses for the Hero fit on this camera.

Any real technical information on the Hero 3 would be greatly appreciated.